The present invention relates to an improvement of an electrical connecting device such as a fuse box, a relay box, a junction block or the like for an automotive vehicle usable for the purpose of protecting electrical circuits, controlling signals or branching or connecting electrical circuits.
FIG. 8(A) is a perspective view of a conventional fuse box, particularly illustrating essential components constituting the fuse box in the disassembled state. FIG. 8(B) is a fragmentary perspective view of the conventional fuse box, particularly illustrating the assembled fuse box in the exploded state. As shown in the drawings, the fuse box is composed of an electrical insulating case 1, a terminal engagement member 7, terminals 10 and fuses 12.
The electrical insulating case 1 is designed in the form of a rectangular electrical insulating case composed of an upper wall 1a, fore and rear side walls 1b and left-hand and right-hand side walls 1c, and fore and rear rows of terminal accommodating chambers 3 are arranged in the side-by-side relationship in the longitudinal direction while a partition plate 2 is interposed between the fore and rear rows of terminal accommodating chambers 3. Tab insert holes 4 are formed through the upper wall 1a so as to allow a pair of tads (blade terminals) for a fuse 12 to be inserted therethrough. As shown in FIG. 11 and FIG. 12, a flexible terminal engagement arm 5 extending toward the tab insert hole 4 side is disposed on the partition plate 2 side in each terminal accommodating chamber 3, and an engagement projection 5a adapted to be engaged with an engagement hole 10b on the terminal 10 is formed at the free end of the terminal engagement arm 5. In addition, engagement rod insert passages 6 are formed through the left-hand and right-hand side walls 1c on the electrical insulating case 1 so as to allow engagement rods 8 of a terminal engagement member 7 to be inserted through the engagement rod insert passages 6 from one side wall to the other one of the electrical insulating case 1.
The terminal engagement member 7 is designed in the U-shaped contour corresponding to the fore and rear rows of terminal accommodating chambers 3 of the electrical insulating case 1 while a pair of engagement rods 8 are connected to each other via a joint plate 9. A terminal 10 includes a base plate 10a of which one serves as an electrical contact portion 10.sub.1 and of which other end serves as an electrical connecting portion 10.sub.2 which is integrated with to a cable 11. The electrical contact portion 10.sub.1 is composed of a base plate portion 10a having an engagement hole 10b formed therethrough, opposite upright standing side walls 10b, an opposing pair of resilient contact pieces 10d formed by inward folding while extending from the foremost ends of the side walls 10c via curved parts and an opposing pair of folded pieces 10e formed by inward folding while extending from both the side walls 10c.
With the conventional fuse box shown in FIG. 8, when a terminal 10 is inserted into a terminal accommodating chamber 3 of the electrical insulating case 1 with an inclined attitude as shown in FIG. 9, it is accommodated in the terminal accommodating chamber 3 while its inclined attitude is kept unchanged as represented by an arrow-shaped mark in the drawing. While the terminal 10 is accommodated in the terminal accommodating chamber 3 in that way, there arise malfunctions that it can not correctly be connected to a tab 12a of the fuse 12, and moreover, an engagement projection 5a of a terminal engagement arm 5 shown in FIG. 11(A) can not be engaged with the engagement hole 10b due to the positional offset of the former away from the latter. In addition, when the engagement rod 8 is inserted through the engagement rod insert passage 6 with an inclined attitude due to the wide width of the terminal accommodating chamber 3 as shown in FIG. 10, the foremost end of the engagement rod 8 collides against a partition wall 3a of the terminal accommodating chamber 3 or the electrical contact portion 10.sub.1 of the terminal 10 as represented by an arrow-shaped mark in the drawing, causing in the engagement rods 8 and the electrical contact portions 10a to be damaged or injured due to the forcible collision therebetween.
FIG. 11(A) and FIG. 12(B) illustrate a double engaged state where the terminal 10 is inserted into the terminal accommodating chamber 3 with a normal attitude, whereby the engagement projection 5a of the terminal engagement arm 5 is engaged with the engagement hole 10b of the terminal 10 to establish primary engagement therebetween, and thereafter, the engagement rod 8 is engaged with a shoulder of the electrical contact portion 10.sub.1 of the terminal 10 to establish secondary engagement therebetween. However, there is a possibility that the terminal 10 is inserted into the terminal accommodating chamber 3 with a reverse attitude as shown in FIG. 11(B). This is because of a necessity for maintaining a slight gap between the side wall 10c of the terminal 10 and the partition plate 2 for the purpose of assuring that the terminal 10 is smoothly inserted into the terminal accommodating chamber 3 while each terminal engagement arm 5 is squeezed toward the partition plate 2 by the base plate portion 10a of the terminal 10 as illustrated in FIG. 12(A). With this construction, when the terminal 10 is partially inserted into the terminal accommodating chamber 3 or it is inserted into the same with a reverse attitude, it is practically difficult to visually recognize the foregoing malfunction from the outside. Thus, terminal insertion is achieved without any recognition of this malfunction.
In addition, as shown in FIG. 13, since terminal engagement arms 5 are formed independently of the opposite surfaces of the partition plate 2 in the terminal accommodating chambers 3 with the partition plate 2 interposed therebetween, deflecting spaces v.sub.1 and v.sub.2 should be prepared for the terminal engagement arms 5 in the terminal accommodating chambers 3. Consequently, the volumetric capacity assumed by the terminal accommodating chambers 3 for the terminals 10 is unavoidably enlarged in the presence of the aforementioned gap, whereby a width W.sub.1 of the electrical insulating case 1 is enlarged correspondingly.